Devices for collecting samples of seabed materials, in particular those which are suitable for deployment from a small fishing vessel, for example a fishing boat 10 to 12 meters in length, typically comprise an open cavity which is closable by one or two curved jaws, or have instead, two or more curved clamshell buckets which close together. Closure is generally effected by a spring mechanism which is cocked on the surface and which is released upon contact with the bottom, by fall of a weight released by contact with the bottom, or by an upward pull on the cable which recovers the sampler. However, tools of these types are generally unsuccessful in collecting samples from hard or compacted bottoms because they fail to penetrate on impact. The limitation of penetration arises in part from the curvilinear configuration of the jaws at their ends, and in part because the sampler is light in weight. In addition, when multi-jaw type devices close on samples from bottoms comprising gravel or coarser material, the jaws are frequently prevented from complete closure by cobbles or boulders which catch in the opening, thus allowing finer material to be washed out during recovery of the tool. When the closure is effected by an upward pull on the recovery cable, the sampler is unweighted at the moment when greatest weight is required to maintain penetration during closure. Furthermore, such devices yield only a single sample. To assess the variability of the bottom, several casts must be made, necessitating anchorage of the vessel. If the vessel is not anchored, the casts may represent different areas of the bottom as the vessel drifts between the casts.